1. Field of the Invention
The invention relates to hot air sterilization and, in particular, to self-contained hot air sterilizers with forced cooling to reduce sterilization cycle times.
2. Description of the Prior Art
Certain medical practices such as small dental and/or orthodontic practices require the availability of large numbers of instruments during a day in the treatment of many patients. In order to reduce the total number of instruments needed to support such practices, sterilization turn around times must be as short as possible. Accordingly, sterilizers with rapid cooling cycles are valuable to such individual practices.
Dry heat sterilization is increasingly becoming the method of choice for sterilizing medical instruments with carbide and carbon steel components. Such sterilization provides safety for all instruments which are chemically and moisture sensitive by introducing no foreign substances and by effectively eliminating moisture in the sterilizing atmosphere.
Medical dry heat sterilizers previously available for use in a practitioner's office typically have used the method of conductive heat transfer both to elevate the instrument loads to a sterilizing temperature and thereafter reduce the temperature of the instruments to a usable level.
Other approaches have been suggested. One suggested approach has been to provide forced air heating for sterilization but to make no provision for cooling. Another approach has been to provide forced air heating within a sterilizing chamber followed by forced air cooling of the outside of the sterilizing chamber walls. Still another suggested approach is the forced air heating and cooling of the contents of a sterilizing chamber by a single fan along a single air flow path through the sterilizing chamber.
One disadvantage suffered by all of these approaches with forced air cooling cycles is that cooling air is circulated through the sterilizer in such a way that it cools the sterilizing air heat source as well as the instruments and other objects being sterilized. In some approaches, cooling air is directed across the heat source before it is passed into the sterilizing chamber and therefore cools the heat source before cooling the contents of the chamber. In some approaches the cooling air must also cool the fan which had been used to circulate heated air through the sterilizing chamber. Cooling time for such sterilizers is extended by the time needed to additionally cool the heat source, and/or the hot air circulating fan.